I'm too old to be sucking my thumb. but i've tried everything and nothing seems to work. help!

Deal with BasicIssue: Behavior not culturally endorsed & can displace/damage teeth/bite over time. Back to basics: why do humans of any age suck their thumb? Could it be associating food/being fed with a sense of relief, being cared for, having value, especially in situations in which fears overpower sense of feeling loved & of value in this world; especially if events threatening confidence keep recurring? Look within.